feat: Support unmarshal resultset into orm receiver

Related to #800

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

client/data.go

@@ -134,6 +134,7 @@ func (c *GrpcClient) handleSearchResult(schema *entity.Schema, outputFields []st
 	for i := 0; i < int(results.GetNumQueries()); i++ {
 		rc := int(results.GetTopks()[i]) // result entry count for current query
 		entry := SearchResult{
+			sch:         schema,
 			ResultCount: rc,
 			Scores:      results.GetScores()[offset : offset+rc],
 		}

client/results.go

@@ -1,6 +1,10 @@
 package client
 
 import (
+	"go/ast"
+	"reflect"
+
+	"github.com/cockroachdb/errors"
 	"github.com/milvus-io/milvus-sdk-go/v2/entity"
 )
 
@@ -9,6 +13,9 @@ import (
 // Fields contains the data of `outputFieleds` specified or all columns if non
 // Scores is actually the distance between the vector current record contains and the search target vector
 type SearchResult struct {
+	// internal schema for unmarshaling
+	sch *entity.Schema
+
 	ResultCount  int // the returning entry count
 	GroupByValue entity.Column
 	IDs          entity.Column // auto generated id, can be mapped to the columns from `Insert` API
@@ -44,6 +51,66 @@ func (sr *SearchResult) Slice(start, end int) *SearchResult {
 	return result
 }
 
+func (sr *SearchResult) Unmarshal(receiver interface{}) (err error) {
+	err = sr.Fields.Unmarshal(receiver)
+	if err != nil {
+		return err
+	}
+	return sr.fillPKEntry(receiver)
+}
+
+func (sr *SearchResult) fillPKEntry(receiver interface{}) (err error) {
+	defer func() {
+		if x := recover(); x != nil {
+			err = errors.Newf("failed to unmarshal result set: %v", x)
+		}
+	}()
+	rr := reflect.ValueOf(receiver)
+
+	if rr.Kind() == reflect.Ptr {
+		if rr.IsNil() && rr.CanAddr() {
+			rr.Set(reflect.New(rr.Type().Elem()))
+		}
+		rr = rr.Elem()
+	}
+
+	rt := rr.Type()
+	rv := rr
+
+	switch rt.Kind() {
+	case reflect.Slice:
+		pkField := sr.sch.PKField()
+
+		et := rt.Elem()
+		for et.Kind() == reflect.Ptr {
+			et = et.Elem()
+		}
+
+		candidates := parseCandidates(et)
+		candi, ok := candidates[pkField.Name]
+		if !ok {
+			// pk field not found in struct, skip
+			return nil
+		}
+		for i := 0; i < sr.IDs.Len(); i++ {
+			row := rv.Index(i)
+			for row.Kind() == reflect.Ptr {
+				row = row.Elem()
+			}
+
+			val, err := sr.IDs.Get(i)
+			if err != nil {
+				return err
+			}
+			row.Field(candi).Set(reflect.ValueOf(val))
+		}
+		rr.Set(rv)
+	default:
+		return errors.Newf("receiver need to be slice or array but get %v", rt.Kind())
+	}
+	return nil
+}
+
 // ResultSet is an alias type for column slice.
 type ResultSet []entity.Column
 
@@ -71,3 +138,87 @@ func (rs ResultSet) GetColumn(fieldName string) entity.Column {
 	}
 	return nil
 }
+
+func (rs ResultSet) Unmarshal(receiver interface{}) (err error) {
+	defer func() {
+		if x := recover(); x != nil {
+			err = errors.Newf("failed to unmarshal result set: %v", x)
+		}
+	}()
+	rr := reflect.ValueOf(receiver)
+
+	if rr.Kind() == reflect.Ptr {
+		if rr.IsNil() && rr.CanAddr() {
+			rr.Set(reflect.New(rr.Type().Elem()))
+		}
+		rr = rr.Elem()
+	}
+
+	rt := rr.Type()
+	rv := rr
+
+	switch rt.Kind() {
+	// TODO maybe support Array and just fill data
+	// case reflect.Array:
+	case reflect.Slice:
+		et := rt.Elem()
+		if et.Kind() != reflect.Ptr {
+			return errors.Newf("receiver must be slice of pointers but get: %v", et.Kind())
+		}
+		for et.Kind() == reflect.Ptr {
+			et = et.Elem()
+		}
+		for i := 0; i < rs.Len(); i++ {
+			data := reflect.New(et)
+			err := rs.fillData(data.Elem(), et, i)
+			if err != nil {
+				return err
+			}
+			rv = reflect.Append(rv, data)
+		}
+		rr.Set(rv)
+	default:
+		return errors.Newf("receiver need to be slice or array but get %v", rt.Kind())
+	}
+	return nil
+}
+
+func parseCandidates(dataType reflect.Type) map[string]int {
+	result := make(map[string]int)
+	for i := 0; i < dataType.NumField(); i++ {
+		f := dataType.Field(i)
+		// ignore anonymous field for now
+		if f.Anonymous || !ast.IsExported(f.Name) {
+			continue
+		}
+
+		name := f.Name
+		tag := f.Tag.Get(entity.MilvusTag)
+		tagSettings := entity.ParseTagSetting(tag, entity.MilvusTagSep)
+		if tagName, has := tagSettings[entity.MilvusTagName]; has {
+			name = tagName
+		}
+
+		result[name] = i
+	}
+	return result
+}
+
+func (rs ResultSet) fillData(data reflect.Value, dataType reflect.Type, idx int) error {
+	m := parseCandidates(dataType)
+	for i := 0; i < len(rs); i++ {
+		name := rs[i].Name()
+		fidx, ok := m[name]
+		if !ok {
+			// maybe return error
+			continue
+		}
+		val, err := rs[i].Get(idx)
+		if err != nil {
+			return err
+		}
+		// TODO check datatype
+		data.Field(fidx).Set(reflect.ValueOf(val))
+	}
+	return nil
+}

client/results_test.go

@@ -0,0 +1,109 @@
+package client
+
+import (
+	"testing"
+
+	"github.com/milvus-io/milvus-sdk-go/v2/entity"
+	"github.com/stretchr/testify/suite"
+)
+
+type ResultSetSuite struct {
+	suite.Suite
+}
+
+func (s *ResultSetSuite) TestResultsetUnmarshal() {
+	type MyData struct {
+		A int64     `milvus:"name:id"`
+		V []float32 `milvus:"name:vector"`
+	}
+	type OtherData struct {
+		A string    `milvus:"name:id"`
+		V []float32 `milvus:"name:vector"`
+	}
+
+	var (
+		idData     = []int64{1, 2, 3}
+		vectorData = [][]float32{
+			{0.1, 0.2},
+			{0.1, 0.2},
+			{0.1, 0.2},
+		}
+	)
+
+	rs := ResultSet([]entity.Column{
+		entity.NewColumnInt64("id", idData),
+		entity.NewColumnFloatVector("vector", 2, vectorData),
+	})
+	err := rs.Unmarshal([]MyData{})
+	s.Error(err)
+
+	receiver := []MyData{}
+	err = rs.Unmarshal(&receiver)
+	s.Error(err)
+
+	var ptrReceiver []*MyData
+	err = rs.Unmarshal(&ptrReceiver)
+	s.NoError(err)
+
+	for idx, row := range ptrReceiver {
+		s.Equal(row.A, idData[idx])
+		s.Equal(row.V, vectorData[idx])
+	}
+
+	var otherReceiver []*OtherData
+	err = rs.Unmarshal(&otherReceiver)
+	s.Error(err)
+}
+
+func (s *ResultSetSuite) TestSearchResultUnmarshal() {
+	type MyData struct {
+		A int64     `milvus:"name:id"`
+		V []float32 `milvus:"name:vector"`
+	}
+	type OtherData struct {
+		A string    `milvus:"name:id"`
+		V []float32 `milvus:"name:vector"`
+	}
+
+	var (
+		idData     = []int64{1, 2, 3}
+		vectorData = [][]float32{
+			{0.1, 0.2},
+			{0.1, 0.2},
+			{0.1, 0.2},
+		}
+	)
+
+	sr := SearchResult{
+		sch: entity.NewSchema().
+			WithField(entity.NewField().WithName("id").WithIsPrimaryKey(true).WithDataType(entity.FieldTypeInt64)).
+			WithField(entity.NewField().WithName("vector").WithDim(2).WithDataType(entity.FieldTypeFloatVector)),
+		IDs: entity.NewColumnInt64("id", idData),
+		Fields: ResultSet([]entity.Column{
+			entity.NewColumnFloatVector("vector", 2, vectorData),
+		}),
+	}
+	err := sr.Unmarshal([]MyData{})
+	s.Error(err)
+
+	receiver := []MyData{}
+	err = sr.Unmarshal(&receiver)
+	s.Error(err)
+
+	var ptrReceiver []*MyData
+	err = sr.Unmarshal(&ptrReceiver)
+	s.NoError(err)
+
+	for idx, row := range ptrReceiver {
+		s.Equal(row.A, idData[idx])
+		s.Equal(row.V, vectorData[idx])
+	}
+
+	var otherReceiver []*OtherData
+	err = sr.Unmarshal(&otherReceiver)
+	s.Error(err)
+}
+
+func TestResults(t *testing.T) {
+	suite.Run(t, new(ResultSetSuite))
+}